Lead zirconate titanate (PZT) has been investigated as a FE material for use in non-volatile data storage, such as FE Random Access Memory (FERAM). However, PZT is not compatible with conventional semiconductor processing techniques and is not scalable because the PZT loses its FE properties at lower thicknesses and, therefore, has integration issues.
Hafnium silicate (HfSiOx) is a high-k dielectric material and has been investigated as a replacement ferroelectric material for PZT. Hafnium silicate is polymorphic and may form in monoclinic, tetragonal, cubic, or orthorhombic crystal structures, with each of the crystal structures having multiple possible crystallographic orientations, such as the (111) or (200) crystallographic orientations. Hafnium silicate is conventionally formed with the (111) crystallographic orientation being the dominant formed crystallographic orientation.
Titanium nitride is a polymorphic material and may form many crystal structures, with each crystal structure having multiple possible crystallographic orientations, such as the (001), (002), (100), (110), (111), or (200) crystallographic orientations. Titanium nitride is conventionally formed in the cubic phase and has multiple crystallographic orientations, with the (200) crystallographic orientation often being the dominant formed crystallographic orientation.
It would be desirable to have improved methods of forming hafnium silicate or other FE materials, such that a desired crystallographic orientation of the ferroelectric material can be achieved.